Switched to using `bitmask` module from `stsci.tools` instead of importing this functionality from `drizzlepac` and `skymatch`. Also, RMS of corrections is now computed in the RAW space. Finally - a minor bug fix that could make `acs_destripe()` crash under a very unlikely set of circumstances.
Switched to using `bitmask` module from `stsci.tools` instead of importing this functionality from `drizzlepac` and `skymatch`. Also, RMS of corrections is now computed in the RAW space. Finally - a minor bug fix that could make `acs_destripe()` crash under a very unlikely set of circumstances.


git-svn-id: ae5d535d8549566df64d2c38e8f7097ffa427e83@38691 fe389314-cf27-0410-b35b-8c050e845b92

jhunkeler/acstools